1. Field of the Invention
The present invention relates to activity sensors that will sense motion and thus activity, and which is suitable for use for sensing activity of people and animals.
2. Description of the Prior Art
Various activity or motion sensors have been advanced, which measure accelerations in selected axes. One such device is sold under the mark RunAlert sold by RunTronics Incorporated, 1301 Shoreway Road, Belmont, Calif. 94002. This device is used by runners to provide a measure of acceleration loading during jogging. The RunAlert is made so that it will provide a beeping sound to indicate when a specific acceleration has been achieved, and in this way determine whether or not excessive loads are being placed on the legs and joints of the body due to impact stress. The RunAlert device is essentially a "G" meter that can be set at successively higher levels to determine when the acceleration or "G" forces exceed a set level. Only an audio signal is provided with this device.
Additionally, activities of deer have been monitored through the use of a mercury "tip" switch device mounted onto a collar on the animal. Such a device and its operation is discussed in an article entitled "Reliability of Motion-Sensitive Radio Collars for Estimating Activity of Black-Tailed Deer", M. P. Gillingham and F. L. Bunnell; J. Wildl, Manage, 49(4):951-958 (1985). This article indicates that motion sensing to monitor activities of deer and other animals has been attempted, but that the accuracy of the then existing devices was questionable. Particular problems were encountered in sensing slow movements which resulted in low accelerations.
Thus, activity sensors for use both by humans and in wild animal research are highly valuable for determining the activity levels, and with the ability to provide an electrical signal which can be stored and which does not require large power supplies, or complex circuitry.